FFT_support.cpp

   1 #include "FFT.h"\r
   2 #include <cstdio>\r
   3 #include <cmath>\r
   4 \r
   5 /* Use Q15 fixed point format (1 sign bit plus 15 fractional bits) */\r
   6 #define FIXED_POINT 15\r
   7 #define WORD_SIZE   16\r
   8 \r
   9 #define WORDS_PER_LINE 8\r
  10 #define WORDS_PER_GROUP 1\r
  11 \r
  12 mem input_a_re, input_a_im, input_b_re, input_b_im, output_a_re, output_a_im, output_b_re, output_b_im, twiddle_re, twiddle_im; \r
  13 \r
  14 int to_fixed(float n)\r
  15 {\r
  16         int res = (int)(n * (1 << FIXED_POINT));\r
  17         /* Crop results */\r
  18         if (res > (1 << WORD_SIZE - 1) - 1)\r
  19                 return (1 << WORD_SIZE - 1) - 1;\r
  20         if (res < -(1 << WORD_SIZE - 1))\r
  21                 return -(1 << WORD_SIZE - 1);\r
  22         return res;\r
  23 }\r
  24 \r
  25 float from_fixed(int n)\r
  26 {\r
  27         return n / (float)(1<<FIXED_POINT);\r
  28 }\r
  29 \r
  30 void print_mem(mem m, int offset, int size, bool fixed)\r
  31 {\r
  32         int i;\r
  33         for(i = offset;i<offset+size;i++)\r
  34         {\r
  35                 if (fixed)\r
  36                         printf("%0.4f", from_fixed(get_mem(m->id, i)));\r
  37                 else\r
  38                         printf("%04hx", (short)get_mem(m->id, i));\r
  39                 if ((i + 1) % WORDS_PER_LINE == 0)\r
  40                         printf("\n");\r
  41                 else if ((i + 1) % WORDS_PER_GROUP == 0)\r
  42                         printf(" ");\r
  43         }\r
  44         if (i % WORDS_PER_LINE != 0)\r
  45                 printf("\n");\r
  46 }\r
  47 \r
  48 \r
  49 void pre_run()\r
  50 {\r
  51         int i;\r
  52         /* Assign memories, at least for the first stage */\r
  53         input_a_re   = alloc_mem(P0M0);\r
  54         input_a_im   = alloc_mem(P1M0);\r
  55         input_b_re   = alloc_mem(P2M0);\r
  56         input_b_im   = alloc_mem(P3M0);\r
  57         \r
  58         twiddle_re   = alloc_mem(P4M0);\r
  59         twiddle_im   = alloc_mem(P4M1);\r
  60         \r
  61         /* TODO: Init memory and twiddles */\r
  62         for (i=0;i<PARAM_N_t/2;i++)\r
  63         {\r
  64                 set_mem(twiddle_re->id, i, to_fixed(cos(i*2*M_PI/PARAM_N_t)));\r
  65                 set_mem(twiddle_im->id, i, to_fixed(sin(i*2*M_PI/PARAM_N_t)));\r
  66         }\r
  67         \r
  68         for (i=0;i<PARAM_N_t;i++)\r
  69         {\r
  70                 /* We take the sine from 0 to 2*2*Pi, ie two periods. We divide \r
  71                  * the value by PARAM_N_t to prevent overflow. */\r
  72                 int value = to_fixed(sin((float)i*2*2*M_PI/PARAM_N_t)/PARAM_N_t);\r
  73 \r
  74                 if (i<PARAM_N_t/2)\r
  75                 {\r
  76                         if (i % 2 == 0) {\r
  77                                 set_mem(input_a_re->id, i, value);\r
  78                                 set_mem(input_a_im->id, i, 0);\r
  79                         } else {\r
  80                                 set_mem(input_b_re->id, i, value);\r
  81                                 set_mem(input_b_im->id, i, 0);\r
  82                         }\r
  83                 }\r
  84                 else\r
  85                 {\r
  86                         if (i % 2 == 0) {\r
  87                                 set_mem(input_b_re->id, i - PARAM_N_t/2, value);\r
  88                                 set_mem(input_b_im->id, i - PARAM_N_t/2, 0);\r
  89                         } else {\r
  90                                 set_mem(input_a_re->id, i - PARAM_N_t/2, value);\r
  91                                 set_mem(input_a_im->id, i - PARAM_N_t/2, 0);\r
  92                         }\r
  93                 }\r
  94         }\r
  95         \r
  96         printf("re(W)\n");\r
  97         print_mem(twiddle_re, 0, PARAM_N_t/2, true);\r
  98         printf("im(W)\n");\r
  99         print_mem(twiddle_im, 0, PARAM_N_t/2, true);\r
 100         printf("re(in_a)\n");\r
 101         print_mem(input_a_re, 0, PARAM_N_t/2, true);\r
 102         printf("re(in_b)\n");\r
 103         print_mem(input_b_re, 0, PARAM_N_t/2, true);\r
 104         \r
 105 /* Write out memory contents for use by the python simulator */\r
 106         save_mem_range_to_file(input_a_re->id, 0, PARAM_N_t/2, "Memory/sin_a_re.mm");\r
 107         save_mem_range_to_file(input_a_im->id, 0, PARAM_N_t/2, "Memory/sin_a_im.mm");\r
 108         save_mem_range_to_file(input_b_re->id, 0, PARAM_N_t/2, "Memory/sin_b_re.mm");\r
 109         save_mem_range_to_file(input_b_im->id, 0, PARAM_N_t/2, "Memory/sin_b_im.mm");\r
 110         save_mem_range_to_file(twiddle_re->id, 0, PARAM_N_t/2, "Memory/twiddle_re.mm");\r
 111         save_mem_range_to_file(twiddle_im->id, 0, PARAM_N_t/2, "Memory/twiddle_im.mm");\r
 112 }\r
 113 \r
 114 void post_run()\r
 115 {\r
 116         if (PARAM_n_t % 2 == 0) {\r
 117                 /* When the number of stages is even, the \r
 118                  * outputs end up at the left memories again */\r
 119                 output_a_re  = alloc_mem(P0M0);\r
 120                 output_a_im  = alloc_mem(P1M0);\r
 121                 output_b_re  = alloc_mem(P2M0);\r
 122                 output_b_im  = alloc_mem(P3M0);\r
 123         } else {\r
 124                 output_a_re  = alloc_mem(P0M1);\r
 125                 output_a_im  = alloc_mem(P1M1);\r
 126                 output_b_re  = alloc_mem(P2M1);\r
 127                 output_b_im  = alloc_mem(P3M1);\r
 128         }\r
 129         printf("re(out)\n");\r
 130         print_mem(output_a_re, 0, PARAM_N_t/2, true);\r
 131         print_mem(output_b_re, 0, PARAM_N_t/2, true);\r
 132         printf("im(out)\n");\r
 133         print_mem(output_a_im, 0, PARAM_N_t/2, true);\r
 134         print_mem(output_b_im, 0, PARAM_N_t/2, true);\r
 135         \r
 136         printf("re(out)\n");\r
 137         print_mem(output_a_re, 0, PARAM_N_t/2, false);\r
 138         print_mem(output_b_re, 0, PARAM_N_t/2, false);\r
 139         printf("im(out)\n");\r
 140         print_mem(output_a_im, 0, PARAM_N_t/2, false);\r
 141         print_mem(output_b_im, 0, PARAM_N_t/2, false);\r
 142 \r
 143 }\r